Extracellular calcium ion concentration is involved in a variety of biological processes, such as blood clotting, nerve and muscle excitability and bone formation (Cell Calcium 11:319, 1990). Calcium ion receptors, which are present on the membranes of various cells in the body, such as parathyroid and kidney cells (Nature 366:574, 1993; J. Bone Miner. Res. 9, Supple. 1, s282, 1994; J. Bone Miner. Res. 9, Supple. 1, s409, 1994; Endocrinology 136:5202, 1995), are important to the regulation of the extracellular calcium ion concentration. For example, concentration of extracellular calcium ion regulates the bone resorption by osteoclasts (Bioscience Reports 10:493, 1990), secretion of parathyroid hormone (PTH) from parathyroid cells and secretion of calcitonin from C-cells (Cell Calcium 11:323, 1990). Parathyroid hormone (PTH) is an important factor in regulating extracellular calcium ion concentration. Secretion of PTH increases extracellular calcium ion concentration by acting on various cells, such as bone and kidney cells, and the extracellular calcium ion concentration reciprocally inhibits the secretion of PTH by acting on parathyroid cells.
Several classes of calcimimetic compounds have been disclosed for regulating extracellular calcium ion concentration, particularly for reducing or inhibiting secretion of PTH. For example, EP 933354; WO 0021910, WO 96/12697; WO 95/11221; WO 94/18959; WO 93/04373; Endocrinology 128:3047, 1991; Biochem. Biophys. Res. commun. 167:807, 1990; J. Bone Miner. Res. 5:581, 1990; and Nemeth et al., “Calcium-binding Proteins in Health and Disease,” Academix Press, Inc., pp. 33–35 (1987) disclose various agents which interact with calcium receptors.
Dauban et al., Bioorg. Med. Chem. Let. 10:2001–4, 2000, disclose various N1-arylsulfonyl-N2-(1-aryl)ethyl-3-phenylpropane-1,2-diamine compounds as calcimimetics acting on the calcium sensing receptor.